Method of cleaning the faces of grindstones



(No Model.)

, E. J. BONETT. METHOD OF CLEANING THE PAGES 0P GRINDSTONES. No.440,616. Patented Nov. 18, 1890.

UNITED STATES PATENT OFFICE.

EDWIN J. BONETT, OF BERLIN, NEW HAMPSHIRE, ASSIGNOR TO HIMSELF, AND THEBERLIN MILLS COMPANY, OF PORTLAND, MAINE.

METHOD OF CLEANING THE FACES OF GRINDSTONES.

SPECIFICATION forming part of Letters Patent No. 440,616, dated November18, 1890.

Application filed March 10, 1890. Serial No. 343,234, (No model.

T0 at whom, it may concern.-

Be it known that I, EDWIN J. Bonnrr, of Berlin, county of Coos, andState of NewHampshire, a citizen of the United States, have i11- venteda certain new and useful Method of Cleaning the Faces of Grindstones, ofwhich the following is a specification, reference be ing had to theaccompanying drawings.

a My invention is especially adapted for the production of wood pulp.

In all operations for producing wood pulp by mechanical disintegration,so far as I am aware, blocks or pieces of wood are held with their facesagainst the grinding-face of a suitable grinder-such, for instance, as agrindstone or emery-wheel. It has also been customary to preventinjurious heat that would be otherwise produced by friction between thewood and the grinding-surface by keeping the face of the grindstone wet.An objection, however, to this is that after a time the face of thegrindstone becomes foul and water is insufficient to keep it clean.

The invention consists in an improved process of cleaning the faces ofgrindstones generally by directing against their faces a blast of steam.To obtain the best results the steam should not be too dry. \Vhile thismethod has been in practice found to be especially adapted for use ingrinding wood pulp, it may no doubt be used to advantage for otherpurposes as well.

In the accompanying drawings, Figure 1 is a side elevation, partly insection, of my improved apparatus, Fig. 2, a view of the steamjet pipesdetached.

I have illustrated in the drawings a suitable apparatus for practicingmy invention; but any suitable means may, of course, be employed.

Referring to the letters of the drawings, A represents a grinder,consisting of a circular grindstone; B B, blocks of wood being ground,and C C, hydraulically-operated presses for forcing the wood against thegrinding-faces of the stone. D indicates a steam-pipe communicating atone end with any suitable steam-generator. (Not shown in the drawings.)At the other end it is connected with branch pipes D D, which terminatewithin the casing or covering E, which surrounds the stone in closedends provided with numerous perforations, as shown in Fig. 2 of thedrawings. These perforations open toward the face of the grindstone, andare located close to it, so that when the pipe D is open for its passagesteam is forcibly discharged through the perforations against the faceof the stone. I have found it also desirable to prevent the escape ofthe steam from the cover E, so that the face of the grindstone is keptat a proper temperature, and the heat of the steam acting upon the woodtends to cook and soften it, thereby facilitating the action of the machine and producing a better quality of pulp. The blast of steam againstthe face of the stone, by its force, in connection with its moist andgaseous qualities, cleanse the face of the stone from all impurities. Bythe use of a liquidsuch, for instance, as watera portion of the dirtaccumulating in the face of the stone may be washed away; but it isascertained by practical use that this is not so efficacious. By the useof water only the heavier and coarser particles of pulp can be cleansedout from the grain of a stone, while the sharp cutting-edges areimperfectly cleaned.

By my invention I am able to so thoroughly cleanse the stone, even whenit is'run, as in practice it usually is, at a very high rate of speed,as to produce one-third more wood pulp than where former methods havebeen employed.

I am aware that it is not new to merely keep the face of the grindstonecovered with steam during the process of grinding; but this isclearlydistinguishable from my invention.

\Vhat I claim is The method of cleansing grindstones, which consists indischarging a blast of steam directly against the working-face of thegrinder.

In testimony whereof I have hereunto subscribed my name this 5th day ofMarch, A. D. 1890.

EDWVIN J. BONETT.

Witnesses:

ALEX. P. BROWNE, JOHN H. TAYLOR.

